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    <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Document</title>
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    <body>
        <!-- 
        1.u1里面只能放li,li里面可以放置其他标签
        2.默认是黑色实心圆
        3.type,disc  circle square none(用的多)
        -->
        <ul type="none">
            <li>xxx</li>
            <li>xxx</li>
            <li>xxx</li>
        </ul>
    </body>
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